After receiving overwhelming bipartisan support in the California State Assembly, Brown approved AB 351, in effect banning any state assistance with federal enforcement of "indefinite detention" of vaguely defined "enemy combatants," including American citizens, without due process, as outlined in the the 2012 National Defense Authorization Act.

Among other points of legal controversy, President Barack Obama’s signing of the NDAA has sparked particular legal backlash over its provisions on indefinite detention, contained in section 1021. AB 351 now prohibits any future “local entities from knowingly using state funds ... to engage in any activity that aids an agency of the Armed Forces of the United States in the detention of any person within California for purposes of implementing Sections 1021.”

A number of states have raised legal challenges against the NDAA, claiming that aspects of the law violate First Amendment and Fifth Amendment rights. According to PolicyMic, section 1021 has also been denounced internationally, with opposition from the ACLU, Amnesty International, Human Rights Watch, the Center for Constitutional Rights, the Cato Institute and the Council on American-Islamic Relations. The ACLU also views the NDAA’s scope of indefinite detentions as “particularly dangerous because it has no temporal or geographic limitations, and can be used by this and future presidents to militarily detain people captured far from any battlefield."

According to the Tenth Amendment Center, state Rep. Tim Donnelly (R-San Bernardino), author of AB 351, said, “Indefinite detention, by its very definition, means we are throwing away the basic foundations of our Constitution.” Donnelly also claimed AB 351 "will prevent California from implementing indefinite detention for any reason.”

Although Alaska and Virginia have passed similar legislation, California’s AB 351 goes further in using the restriction of state funds to accomplish a broader prevention of indefinite detention. The state's successful passage of the more aggressive ban on assistance with federal indefinite detentions -- built on bipartisan support -- may indicate a better chance of success for other states launching legal battles against controversial NDAA measures.